Group 4 soybeans score high marks

In 1992, Chicot County, Ark., Extension agent Carl Hayden started looking at Group 4 soybeans. A few producers in the southeast Arkansas county had brought in some Midwest varieties and, at the same time, Hayden had some plot work devoted to Group 4s.

“The yield for a dryland study I did was 58 bushels. Back in 1992, we weren't growing very many 58-bushel beans period, much less dryland beans. That certainly piqued my interest,” says Hayden, who spoke at the Tri-State Soybean Forum and Southern Soybean Conference in Dumas, Ark., on Jan. 4.

In 1996, Hayden received a call saying Avery Farms had cut some 70-bushel Group 4s. Intrigued, Hayden measured the field twice. He came up with 69.9 bushels per acre.

“At that time, as far as I know, we hadn't grown any 70-bushel beans (this year, that same field cut 79.4 bushels). I had a Group 5 demonstration right across the turn row from that and I kept thinking, ‘Man, if he made 70 bushels on those Group 4s, we're sitting pretty with these great looking Group 5s. We're going to have some outstanding yields.’”

But when Hayden went back to harvest the Group 5s, 60 bushels was tops. That isn't bad, of course, but that 10-bushel drop-off piqued Hayden's interest in the Group 4s even further.

“The next year, I planted groups 4, 5 and 6 (on 56 different variety plots). The top plot yield was a Group 4 at 74 bushels. The field that had made 70 bushels the year before was put back in a Group 4, too. It yielded 75 bushels the next time around.”

Since then, soybeans on Avery Farm have been planted as close inside the optimum Group 4 time window as possible. Hayden says 2001 was the earliest they had been planted — April 6. The top yields have ranged from 69 to 74 bushels.

This year, farmers in Chicot County ran into the same trouble everyone else did: rain. “We didn't get the beans harvested in August prior to the rains, so we had some deterioration. Even though 69 bushels was the high yield, that particular variety had 18 percent damage. We saw damage anywhere from 4 percent to 38 percent.

“One other thing we tried was applying Quadris to half the fields. We harvested that half separately and found that there was a 6-bushel average difference between the treated and untreated. Where we treated with Quadris we averaged 6 percent damage; where we did not treat we averaged 18 percent damage.”

There are a lot of buckshot soils in Chicot County, says Hayden. For a few years, common thought was that Group 4s might not fit on such ground. That changed after farmers had grown them for a while. Last year, about 60 percent of the county's soybeans were Group 4.

“There's another reason we've gone to Group 4s, though. In 2000, green bean syndrome tore our Group 5s up. Everyone was running scared and didn't want to worry about having to spray for stinkbugs three or four times. As a result, they went with Group 4s.”

When irrigating buckshot fields, farmers typically look at planting between April 10 and May 10.

On well-drained soils, the earlier the planting the better. Hayden says the county had a lot of beans planted the first week of April last year.

Harvesting early beans is something that must be addressed, says Hayden. “I don't think we'll be seeing the kinds of problems with rain we had this past August very often. But we have a problem with shattering and don't want beans coming out in hot temperatures and not being able to harvest them.

“Last harvest, we had some producers that went all Group 4s. That put pressure on the combines and meant the corn crop was behind in getting out. Elevators had trouble getting the soybeans in. Lines of trucks were backed up.”

Most of the Group 4s fields Chicot County plants are minimum-till. Last year there were quite a few beans planted no-till behind corn around April 15. Those beans made about 55 bushels dryland, “which is pretty impressive.”

Regarding varieties, when Roundup Ready varieties came along and were planted beside conventionals, the yields were essentially the same, says Hayden. If you had a good variety, it didn't matter whether it was a Roundup Ready or a conventional.

“That's what our test plots show. The main thing is to pick a variety suitable to the soils you're planting into.”

Farmers in his county had a tremendous problem with grasshoppers this year, says Hayden.

“I actually saw a 300-acre field of 6-inch to 8-inch Group 4s. The next day they were about 2 inches tall. I'd never seen anything like it. The farmer sprayed and the crop recovered.”

Stinkbugs were a problem in some Group 4s. Those problems were primarily in areas around heavy cover where the pests could overwinter.

“We didn't have nearly the stinkbug damage in Group 4s that we did in Group 5s.”

Hayden has also seen some sudden death syndrome. When SDS shows up, it's usually during a good soybean year, he says.

“In every instance where we saw SDS, the field had been planted in the same variety at least two years in a row. In most cases, the variety hadn't changed for three years and the field hadn't been rotated.”